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PubMed1969

Infusion of long-chain fatty acid anions by continuous-flow centrifugation.

We have developed a method for the rapid infusion into plasma of large amounts of long-chain free fatty acids (FFA). Unanesthetized dogs were connected by a peripheral artery to a closed, continuousflow centrifuge from which cells and plasma emerged in separate lines. Sodium oleate was infused directly into the plasma line before cells and plasma were recombined and returned to the animal through a peripheral vein.The centrifugation procedure itself produced only small changes in circulating levels of glucose, FFA, and electrolytes. Plasma flow rates as high as 100 ml/min could be maintained, and centrifugations of 12 hr were accomplished without complications. During centrifugation, sodium oleate was infused at rates up to 80 muEq/kg per min for 2.5 hr; the maximum molar ratio of FFA to albumin without hemolysis was 10:1. Plasma FFA levels rose rapidly after infusions were started and reached constant elevated levels within 15-20 min. Oleate infusion at 10-50 muEq/kg per min produced a rise in plasma FFA proportional to the infusion rate. The maximum increment in plasma FFA above control values was 1.66 muEq/ml. When infusions ended, plasma FFA declined rapidly to control levels. Oleate infusion at rates below 30 muEq/kg per min did not reduce levels of other plasma FFA. Infusion at high rates was accompanied by a marked fall in blood glucose. This method permits adminsitration of long-chain fatty acids in sufficient quantities to study their individual metabolic effects, and provides a new way to supply lipid calories parenterally.

Animals↗

PubMed2000

Production of transgenic rabbits using centrifuged pronuclear zygotes.

Superovulation of female rabbits was induced by subcutaneous injection(s) of porcine FSH. Zygotes were recovered 17 to 19 hr after hCG injection and were classified into two categories under a microscope equipped with Nomarski interference-contrast optics at x 200 magnification: (A) zygotes with clearly visible pronuclei, or (B) zygotes with visualized pronuclei after 10 min centrifugation at 12,000 x g. No significant difference between strains was found in the proportion of category-A zygotes (JW 72.6% vs NZW 79.3%). Pronuclei of category-A zygotes were located in the center of the cytoplasm, and the pronuclei of category-B zygotes were slightly moved by centrifugation toward the mass of cytoplasmic lipid droplets. Exogenous DNA solution (5 microg/ml of fusion gene composed of bovine alphaS1-casein promoter and human growth hormone structural gene) was microinjected into the pronucleus of the JW zygotes. The pronucleus of category-A zygotes with a mean volume of 7.4 pl swelled up to 16.6 pl (132% increase), while that of category-B zygotes with a mean volume of 6.1 pl swelled up to 15.9 pl (148% increase). Nevertheless, similar proportions of category-A and category-B zygotes developed into offspring after transfer to recipient females (11.1 and 11.2%, respectively). The efficiency to produce hGH-carrying transgenic rabbits was 0.9% (2/235) from category-A zygotes and 0.5% (1/215) from category-B zygotes (P>0.05). To date, transgenic rabbits have been produced without centrifugation of pronuclear zygotes. However approximately 25% of fertilized rabbit zygotes can be used for DNA microinjection after they have been centrifuged to visualize their pronuclei.

Animals↗

PubMed2001

[Aquatic animals and use of centrifuge in space experiments].

There are some experiments which do not need a centrifuge apparatus in space, however, for other space experiments the use of centrifuge is indispensable as the control. The characteristics of these two types of space experiments are explained. Generally, the more quantitatively the phenomenon is analyzed, the greater the need of centrifuge apparatus becomes. The centrifuge in space can realize various gravity values ranging from 0 to 1 G, and this will extend the present biology to a more universal biology.

Animals↗

PubMed2006

Use of a centrifugation-based, point-of-care device for production of canine autologous bone marrow and platelet concentrates.

OBJECTIVE: To analyze a centrifugation-based, point-of-care device that concentrates canine platelets and bone marrow-derived cells. ANIMALS: 19 adult sexually intact dogs. PROCEDURES: Anticoagulated peripheral blood (60 mL) and 60 mL of anticoagulated bone marrow aspirate (BMA) were concentrated by centrifugation with the centrifugation-based, point-of-care device to form a platelet and a bone marrow concentrate (BMC) from 11 dogs. Blood samples were analyzed on the basis of hemograms, platelet count, and PCV. The BMA and BMC were analyzed to determine PCV, total nucleated cell count, RBC count, and differential cell counts. The BMC stromal cells were cultured in an osteoinductive medium. Eight additional dogs were used to compare the BMC yield with that in which heparin was infused into the bone marrow before aspiration. RESULTS: The centrifugation-based, point-of-care device concentrated platelets by 6-fold over baseline (median recovery, 63.1%) with a median of 1,336 x 10(3) platelets/microL in the 7-mL concentrate. The nucleated cells in BMCs increased 7-fold (median recovery, 42.9%) with a median of 720 x 10(3) cells/microL in the 4-mL concentrate. The myeloid nucleated cells and mononuclear cells increased significantly in BMCs with a significant decrease in PCV, compared with that of BMAs. Stromal cell cultures expressed an osteoblastic phenotype in culture. Infusion of heparin into the bone marrow eliminated clot formation and created less variation in the yield (median recovery, 61.9%). CONCLUSIONS AND CLINICAL RELEVANCE: Bone marrow-derived cell and platelet-rich concentrates may form bone if delivered in an engineered graft, thus decreasing the need for cancellous bone grafts.

Animals↗

PubMed1988

Rapid detection of cytomegalovirus pulmonary infection by bronchoalveolar lavage and centrifugation culture.

Cytomegalovirus infection remains a major cause of morbidity and mortality in marrow transplant recipients. Results of a rapid centrifugation viral culture of bronchoalveolar lavage specimens from 33 marrow transplant recipients with pneumonia were compared with those for conventional viral culture of concurrently or subsequently obtained lung tissue. The centrifugation culture results were also compared to results of cytologic and immunochemical examination of these specimens. Centrifugation culture was positive within 16 hours of inoculation in 22 of 23 (96%) specimens from patients with positive conventional culture of lung tissue. Detection of cells positive for cytomegalovirus by immunofluorescent antibody staining or cytologic identification was less sensitive (59% and 29%, respectively). There was no evidence of cytomegalovirus in specimens from patients without evidence of cytomegalovirus pulmonary infection by any technique. The sensitivity (96%) and specificity (100%) of centrifugation culture of specimens from marrow transplant recipients approach that of viral culture of lung tissue.

Adolescent↗

PubMed1999

[Comparison between centrifugation and sedimentation prior to cultures in the isolation of cytomegalovirus in the urine of renal transplant recipients].

BACKGROUND: To compare the capacity of conventional centrifugation and spontaneous sedimentation to detect the presence of cytomegalovirus (CMV) in urine samples. MATERIAL AND METHODS: We studied urine samples from 45 renal transplant recipients. After decontamination half of each sample was centrifuged (1,500 rpm for 10 minutes) and the other half was allowed to sediment at room temperature for 30 minutes. From the supernatant of each of these 250 microliters was inoculated in a shell-vial (MRC-5). Cultures were incubated for 48 hours at 37 degrees C and stained by an indirect immunofluorescence assay. The samples considered totally toxic were re-inoculated after dilution 1:1 with maintainance medium. RESULTS: Of 845 urine samples analyzed, 743 (88%) were negative and 102 (12%) positive. 66 (7.8%) were considered toxic: 35 (4.1%) partially toxic and 31 (3.6%) totally toxic. Of the centrifuged urine samples 86.2% were positive against 98% of the sedimented samples (p = 0.004). Of the 31 samples considered totally toxic, 17 (2.2%) corresponded with negative urine samples and 14 (13.7%) with positive samples. Off these, 12 (85.7%) were detected in centrifuged samples and 2 (14.3%) in sedimented samples (p = 0.001). CONCLUSIONS: The percentage of toxicity in the urine samples was low (7.8%) which does not seem to suggest the need for systematic dilution of all samples. The sedimentation process enabled us to detect a greater number of urine samples positive for CMV with a lower rate of toxicity of the monolayers. The use of this process would reduce the number of samples requiring reinoculation.

Centrifugation↗

PubMed1975

Coil planet centrifugation and its application to the observation of altered membrane properties of erythrocytes in hepatobiliary disorders.

A coil planet centrifuge (CPC) is an apparatus aiming to obtain a centrifugal force exerting on particles suspended in a fluid in a coiled polyethylene tube (coil) which makes self-rotation around its axis and revolution around the principal axis simultaneously. If a linear osmotic gradient is prepared in the coil and a small amount of blood is applied to it and subjected to centrifugation, one is able to observe the membrane properties of erythrocytes in terms of the shift of hemolysis band appearing in the coil with high accuracy and precision. Coil planet centrifugation was applied to the observation of altered membrane properties of erythrocytes in hepatobiliary diseases. Remarkable shifts of end-point of the hemolysis band going in parallel with the severity of damage were visualized. Study as to its cause revealed that increased free cholesterol content of erythrocyte membrane which was the result of plasma cholesterol Esterstürz due to inhibition of lecithin-cholesterol acyltransferase by stagnant bile acids was responsible for this phenomenon. Elevation of serum bile acid concentration and increased serum leucine-aminopeptidase were closely correlated to the shift of hemolysis end-point toward the low osmolal side. CPC may be useful for detection and chasing the clinical course of patients with hepatobiliary disorders.

Acute Disease↗

PubMed1975

[Purification of coxiella burneti antigen by density gradient centrifugation (author's transl)].

Coxiella burneti, strain Henzerling, Phase II, was recovered from yolk sacs of infected chidken embryos by mechanical separation, treated with Freon and purified by density gradient centrifugation. A J-21 Beckman Centrifuge was applied and the JCF-Z Rotor with a zonal as well as a continuous flow core was used. The technique of producing different types of gradients with a wide range of density (1-60% Sucrose) without a gradient pump is described. With the zonal core a good separation of antigen from unspecific proteins was achieved with 60 Min. at 15000 rpm (Fig. 2-4). The antigens bandet in 1-4 characteristic peaks within the range of 45-49% Sucrose (1,2102-1,2532 g/ml), according to the gradient used. A certain amount of specific fluorescent antigen was also found within the peaks of unspecific protein at densities of 18 -- 20% Sucrose (1,0776-1,0820 g/ml). Centrifugation for more than 1 hour only caused a shift of the antigen peaks into a higher range of density. Using the continuous flow core 2 antigen peaks were found within a density of 43-50% Sucrose (1,1961-1,2341 g/ml). Unspecific protein banded with a peak at 15% Sucrose (1,0612 g/ml); small amounts of specific fluorescent antigen were also found within that density. Approaching equilibrium by centrifuging up to 44 hours at 19000 rpm caused the Coxiella antigens to band at 54% Sucrose (1,2544 g/ml).

Animals↗

PubMed1992

Centrifuges: their development and use in gravitational biology.

The nature of centrifuges and their use in biological research are reviewed historically. Centrifuges are particularly important to research in gravitational biology because the inertial (centrifugal) forces developed by motion can be combined with gravitation to produce gravitational fields other than Earth gravity. In orbiting satellites centrifuges can provide an on-board 1 g environment. A similarity of results from the orbiting and ground-based 1 g controls will provide an essential assurance that the biological responses to the spacecraft environment are the result of changes in the gravitational field. The relationship of biological responses to gravitational fields greater or less than Earth gravity is considered. However, at present there is insufficient equivalent information to decide whether there is or is not a proportionality of response to fields stronger or weaker than Earth gravity.

Acceleration↗

PubMed2003

[Development and application of self-powered short arm human centrifuge].

OBJECTIVE: To present the development and application of a self-powered short arm human centrifuge. METHOD: Self-powered short arm human centrifuge consisted of human power, adjustable resistance trig, short arm and supporting construction parts. It was driven by human power. The short arm turned around the supporting part so artificial gravity is produced. The physical load can be adjusted by the adjustable resistance part. G-level depends on the rotative velocity of the central shaft. Nine healthy male volunteers received self-powered short arm human centrifuge training for 5 min per day with rotative velocity of 30-34 r min-1 for 7 d. Cardiac pumping function was measured before and after training. RESULT: Heart rate (HR) decreased significantly while left ventricular ejection time (LVET) increased significantly after 3 d training, and HR and LVET changed further after 7 d training. Stroke volume increased significantly only after 7 d training. CONCLUSION: Self-powered short arm human centrifuge combines artificial gravity and exercise and included other advantages of safety and economy of construction. Cardiac pumping function could be improved by 7 d training. It may be used for anti-G physiological training or as a countermeasure to counteract the effect of microgravity.

Adaptation, Physiological↗

PubMed2003

Viscoelastic deformation response of red blood cells under conditions of oscillating centrifugal field.

The red cell deformation under the conditions of oscillating centrifugal fields was studied. Experiments were carried out with a modified Cell-Elastometer operating in oscillating mode (0.02 to 0.30 Hz). Gravitational acceleration was sinusoidally modulated between 620 g and 2250 g. At low frequencies (below 0.08 Hz), native red cells followed the applied stress without delay. At 0.09 Hz and up, the cellular deformation was still periodical and included an additional perturbation due to intracellular movements. This perturbation was analysed and quantified. The influence of alterations on the erythrocyte membrane by diamide was analysed to verify the sensitivity of this method. On increasing the membrane stiffness with low concentrations of diamide, the response to oscillatory centrifugal stress was impaired characteristically in terms of amplitude deformation. Based on tangential and centrifugal accelerations, a physical model was developed that describes the basic observable changes on varying the oscillation frequency. From the data it can be concluded that viscoelastic properties of red cells can be analysed and quantified using oscillatory centrifugal accelerations. The described method can become a valid tool to differentiate between membrane alterations or intracellular viscous modifications.

Acceleration↗

PubMed1992

Roentgenographic and mechanical performance of centrifuged cement in a simulated total hip arthroplasty model.

Roentgenographic analysis showed that centrifugation significantly reduced the gross and regional porosity of the cement compared with hand-mixed controls in a simulated total hip arthroplasty model. Static failure test of the prosthetic system demonstrated that the centrifuged cement had significantly greater strength than the hand-mixed cement. Under low-cycle fatigue tests of the same composite models, there was a trend for the centrifuged cement to be stronger than the hand-mixed specimens, although statistically it was not significant. Thus, centrifugation can reduce porosity and significantly improve the static strength of cement in a simulated in vitro total hip replacement model. When cement is used, any possible improvement in the physical properties of bone cement should be considered.

Analysis of Variance↗

PubMedDate not supplied

Mapping size distributions of parenteral fluorocarbon emulsions by a novel method of centrifugal sedimentation followed by densitometry.

A novel method for characterization of size distributions of parenteral fluorocarbon emulsions is described. Prepared emulsions were centrifuged to sediment droplets above predetermined diameters out of a known supernatant sample volume using the Bostok-Stoke's equation. Centrifugation times may be calculated using centrifuge parameters and physical properties of the fluorocarbon oil phase and the dispersion medium. The fluorocarbon content of the supernatant sample volume at successive centrifugation times was determined both by densitometry and by Gas Chromatography. A close correlation was found between the two methods. The density data was processed and converted into a volume distribution histogram by means of a program written in BASIC. The speed, simplicity of use, non reliance on costly equipment and good correlation to absolute particle counting methods makes the density method suitable for submicron size characterization.

Centrifugation↗

PubMed2004

CFD simulation of centrifugal cells washers.

The feasibility of using computational fluid dynamics to guide the design of better centrifuges for processing shed blood is explored here. The velocity field and the rate of protein removal from the shed blood have been studied. The results indicate that computational fluid dynamics could help screen preliminary centrifuge bowl designs thus reducing the number of initial experimental tests required when developing new centrifuge bowls. Though the focus of this work is on washing shed blood the methods developed here are applicable to the design of centrifuge bowls for other blood processing applications.

Blood Cells↗

PubMed1976

Hepatocyte perfusion within a centrifuge.

A centrifuge, as used in blood banks for washing erythrocytes, is shown to be a good perfusion chamber for hepatocyte suspensions being evaluated for potential extracorporeal liver support. The perfusate was cell-free oxygenated--pO2 300 millimeters of mercury--plasma, serum or tissue culture medium. A centrifuge that requires intermittent perfusion cannot deliver sufficient oxygen to maintain prolonged viability. A continuous flow unit can, at a flow of 800 milliliters per minute, support most functions of 100 grams of hepatocytes for six hours and some function for 12 hours. Metabolism of 2-14C tagged pyruvate to 14CO2 is the most useful sensitive measurement of liver function in this system. It is concluded that a centrifuge allowing a constant perfusion of oxygenated plasma into hepatocytes kept within the unit by centrifugal force is a suitable base for extracorporeal liver support.

Animals↗

PubMed1991

Relative enrichment of hematopoietic progenitor cells: efficiency of a repeated density centrifugation.

Low-density cells were prepared from 11 bone marrow samples by centrifugation on Ficoll-sodium diatrizoate. Repeated density gradient centrifugation of the cells collected from the interface of the first gradient removed most nonnucleated erythroid cells. A mean of 47.9% (19.4% to 76.0%) of the mononuclear cells collected after the initial centrifugation were recovered from the interface of the second gradient, whereas 13.3% (3.7% to 34.9%) of the MNCs were counted in the high-density pellet and 38.9% (3.8% to 65.7%) of the MNCs were lost unspecifically. In contrast, a mean of 71.7% (43.0% to 91.3%) of the colony-forming units were recovered from the interface after the second centrifugation (as determined by colony formation assays), whereas only 3.2% (0.5% to 7.0%) were found in the high-density pellet. The unspecific loss of colony-forming units was 25.1% (1.7% to 51.4%). The results demonstrate a relative enrichment of colony-forming units in the culture assay by 1.7 times (average). The method is recommended as an additional preparative step before fluorescence-activated sorting of viable cells, because removal of most erythrocytes and late normoblasts strongly reduces the time required for sorting.

Adolescent↗

PubMed1979

Centrifugation of stallion semen and its storage in large volume straws.

In a study of different methods of handling stallion semen for deep freezing, ejaculates were divided into 3 portions, the first of which was diluted 1:2 with lactose--egg yolk--glycerol diluent and frozen in pellet form. The second aliquot was centrifuged without any diluent and the third portion was initially diluted with an experimental diluent (Merck) and then centrifuged for 5 min at 1000 g. The second and third portions were frozen in large volume straws each of which contained one whole insemination dose of 1 or 2 X 10(8) progressively motile spermatozoa. The addition of a diluent to the semen before centrifugation and freezing (portion 3) resulted in an increase in sperm motility after thawing. Motility was further increased by the use of a recently developed diluent after centrifugation and before freezing. In one fertility trial, 12 of 19 mares (63%) conceived following a single insemination of frozen semen during one oestrous period.

Animals↗

PubMed1988

Human African trypanosomiasis: use of double centrifugation of cerebrospinal fluid to detect trypanosomes.

A double-centrifugation technique for the detection of trypanosomes in samples of cerebrospinal fluid is described and evaluated. The results of the analysis of samples of cerebrospinal fluid from 128 patients with Trypanosoma brucei gambiense sleeping sickness from the Daloa area of Côte d'Ivoire, obtained using single centrifugation, are compared with those obtained using the new method. Double centrifugation is at least twice as sensitive as single centrifugation and results in an increase of 37% in the early detection of late-stage case of the disease. The technique is easily implemented under field conditions.

Animals↗